The present invention relates to a process for manufacturing an electronic display device, comprising a display covered with a protective plate optionally provided with colored optical filters intended to cooperate with this display. The invention applies, generally, to color or monochrome type displays and, in particular, to compact display devices having a miniature display (i.e. having a “microdisplay”).
In a known manner, display devices having a microdisplay such as, for example, those having organic light-emitting diodes (OLEDs), comprise an active zone formed from a pixel matrix and an electrical connection zone which is arranged adjacent to this active zone and which typically comprises an alignment of electrical contacts. These microdisplay devices are manufactured by assembling colored optical filters respectively to color spots of the pixels that form the active part of the microdisplay and that cover a semiconductor substrate typically composed of a silicon wafer. These filters are usually deposited on the inner face of a glass plate that is bonded to the microdisplay, so as to protect it, in the style of an impermeable encapsulation, from the moisture and oxygen of the outside environment.
In general, this assembly is carried out by applying a film of adhesive crosslinkable by ultraviolet radiation over the entire surface of the microdisplay or of the inner face of the protective plate equipped with filters, due to the fact that it is technically difficult to confine this application of adhesive to only the active zone of the microdisplay. The result of this bonding of the protective plate to the microdisplay and of the crosslinking of the adhesive by this radiation through the plate thus assembled is the presence of cured adhesive covering the electrical contacts of the connection zone, which complicates the subsequent operation of “freeing” the contacts via cutting the plate to the right of the separation between the active and connection zones.
To solve this problem of the preservation of the electrical contacts of the microdisplay thus covered by the protective plate, this crosslinkable adhesive has in the past been applied, in particular:                in the form of a bead surrounding the active zone of the microdisplay such as, for example, described in document U.S. Pat. No. 6,825,612 B2, with, as a drawback resulting therefrom, an imperfect protection of the microdisplay by the plate; or        selectively over this active zone by display-printing, which has the drawback of requiring a high degree of precision in the application of the spots of adhesive; or else        by pre-structuring the assembly face of the protective plate to form therein cavities intended to face the electrical contacts and of much greater depth than the thickness of the film of adhesive applied, so that the adhesive is lodged in these cavities, with, as a drawback, the prior required step of structuring the plate.        